Silphenylene-Siloxane Copolymers

More recently, in 1998 and 1999, McKnight et al. [19-21] reported some vinyl-substituted silphenylene siloxane copolymers with exactly alternating structures and varying vinyl content that were synthesized through disUanol diaminosilane polycondensation, as follows ... 

Table 3 OH-terminated silphenylene/siloxane copolymer phases, specially designed for high-temperature work...

Silphenylene-Siloxane Copolymers.—The thermal properties vctsus structure for poly(tetramethyl-p-silphenylensesiloxane) and (tetramethyl-p-silphenylene/di-methylsiloxane) block copolymers have been compared. The homopolymer has a m.p. of 160°C, heat of fusion of 54.4 J/g and Tg of —20°C. The Tg of the copolymer varies monotonically with inojeased dimethylsiloxane content, from — 20 to —123 °C. Data have been reported on the crystallization kinetics and morphology of blends of fractionated poly(tetramethyl-p-silphenylenesiloxanes). The chemical degradation of poly(tetramethyl-/ -silphenylenesiloxane/dimethyl-siloxane) block copolymers by HF has been reported. In 48% HF at 30 °C, preferential attack occurs at the Si—O bond, particularly those of the MejSi—O non-crystalline components, in copolymers containing 15, 35, and 52% poly-dimethylsiloxane. - Further data have been reported on the crystal structure and fold conformation of poly(tetramethyl-/>-silphenylenesiloxane)s, obtained from X-ray diffraction studies. ... 

Et2NC(0)NPhCH iMe2X], ( Si),i" poly(2,2-divinyl-4,4,6,6-tetramethyl-trisiloxane), ( Si), silphenylene-siloxane copolymers, poly(silyl... 

Figure 11.27 29Si-NMR spectrum of a silphenylene-siloxane block copolymer (67 mol % DMS), observed at 59.6 MHz [29]...

Merker, R. L., and M. J. Scoxx Random and block copolymers of poly-(tetramethyl-p-silphenylene-siloxane) and polydimethylsiloxane. J. Polymer ScL 2A, 31 (1964). 

A few years earlier, in 1991, Williams et al. [22] had performed the structural analysis of poly(tetramethyl-p-silphenylene siloxane)-poly(di-methylsiloxane) copolymers (TMPS-DMS copolymers) by Si NMR. These copolymers were obtained by the condensation of bis-hydroxy(tetramethyl-p-silphenylene siloxane) 1 with a, tw-dihydroxy polydimethyl oligosiloxanes, in the presence of a guanidinium catalyst (cf. Scheme 8) ... 

Merker, R. L. Scott, M. J. Haberland, G. G., Random and Block Copolymers of Poly(tetramethyl-p-Silphenylene-Siloxane) and Polydimethylsdoxane. J. Polym. Set, Part A Polym. Chem. 1964,2, 31-44. 

Figure 3.12 The Si-NMR spectrum of a silphenylene-siloxane block copolymer containing 67% dimethylsiloxane with an average silphenylene block length of four and an average dimethylsiloxane block length of seven. Repnnted with permission from ref. 11.

The polycondensation reaction between telechelic hydride and telechelic methoxy siloxane in the presence of very low levels of B(CgFj)3 has been described. The compromise between large polymer content and reasonable molar masses is found by tailoring the addition rate and excess content of L H reagent. Rubinsztajn et al. showed that with silphenylene-co-PDMS copolymers, the reaction was completed... 

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